1. Technical Field
The invention relates generally to the treatment of psychotic symptoms, and more particularly, to predicting whether iloperidone, an iloperidone metabolite, or pharmaceutically-acceptable salts thereof will be efficacious in treating an individual's psychotic symptoms, based on the individual's genotype at one or more single nucleotide polymorphism (SNP) loci.
2. Background Art
Schizophrenia is a psychotic disorder affecting approximately 1% of the US population. It is characterized by the presence of positive symptoms (e.g., hallucinations and delusions) and negative symptoms (e.g., blunted affect and social withdrawal), as well as impairment of cognitive functions. There is much evidence that schizophrenia may not be caused by a single major gene, but rather by several interacting susceptibility loci.
The nature and severity of an individual's schizophrenia may be measured using a number of scales, the most widely used being the Positive and Negative Syndrome Scale (PANSS). A number of PANSS subscales may also be used, such as the PANSS general psychopathology subscale (PANSS-GP), the PANSS positive symptom subscale (PANSS-P), and the PANSS negative symptom subscale (PANSS-N). The PANSS total score (PANSS-T) is comprised of all PANSS subscales.
Perhaps due to the heterogeneity of the underlying disease process, the etiology of schizophrenia has not been identified. Genetic factors are expected to play a role in the response to drug treatment. Several studies have shown that a polymorphism in the serotonin 5-HT2A receptor may be associated with the efficacy of clozapine and risperidone.
Iloperidone is classified as an atypical antipsychotic, most commonly characterized by their relatively low affinity for dopamine D2 receptors and high affinity for serotonin 5-HT2 receptors. Data stemming from the iloperidone clinical program indicate that the response to iloperidone is variable, as is the case with all marketed antipsychotics.